1. Field of the Invention
The present invention relates to a focus adjustment apparatus that performs autofocus (AF) control by performing tracking according to feature information of an object.
2. Description of the Related Art
There has conventionally been discussed a technique for detecting feature information such as a face or a color and executing focusing control based on a range-finding result of a phase difference autofocus (AF) sensor corresponding to a position of the feature information. Japanese Patent Application Laid-Open No. 2010-186004 discuses a technique for performing focus adjustment by phase difference AF by tracking a face area.
Japanese Patent No. 3442426 discusses a technique for storing in advance a relationship between an output of a photometric sensor and an output of an AF sensor as a setting value, and adjusting charge storage time of the AF sensor based on high and low of luminance.
However, because of a principle of the phase difference AF and the face/color detection, features of an object each suited for detection are incompatible to each other. More specifically, for the phase difference AF, high focusing accuracy is acquired in the case of an object having contrast. On the other hand, for the face/color detection, detection of an object is easier in an area having a uniform color such as a skin color for which the phase difference AF is not suited. These opposing features cause an issue that sufficient focusing accuracy cannot be acquired if focusing control is executed in a position where a face or a color has been detected. In the technique discussed in Japanese Patent No. 3442426, the charge storage time of the AF sensor is changed based on the luminance information of the object. In consequence, an issue, namely, reduction in accuracy of the phase difference AF caused by low contrast when AF is executed by using the feature information such as a face or a color, cannot be avoided.